496 CUVIER'S CHINCHILLA CHAP.
to a separate family which will include but the one species,
Fam, 6. CMacMllidae.—This family, likewise South American,
contains three genera,1 all of which agree in having long limbs,
especially the hind-limbs, and a bushy and well-developed tail.
The hair is exceedingly soft, hence the commercial value of
The genus Chinchilla,, containing but a single species, C. lani-
ger, is a small and squirrel-like creature, living at considerable
heights in the Andes. The eyes, as it is a nocturnal creature,
are naturally large; and so also are the ears. The fore-feet have
five toes, the hind-feet only four; they are furnished with feeble
nails. The innermost toe of the hind-foot has a flat and nail-like
claw. There are thirteen dorsal vertebrae, and the long tail has
more than twenty. The clavicle is well developed, as in the
other genera of this family. The large intestine of this animal
is extraordinarily long; the proportions of the different regions
of the gut are shown by the following measurements: small
intestine, 820 mm.; caecum, 125 mm.; large intestine, 1340
mm. Such a disproportion between the large intestine and the
small, to the advantage of the former, is a very strange fact in
the anatomy of this Rodent.
The genus Lagidium (also called Lagotis), which includes
" Cuvier's Chinchilla/* is also a mountain dweller. There are
several species of this genus, which differs from Chinchilla
by the complete abortion of the thumb and of the great toe.
The intestinal proportions are those of Chinchilla. The ears and
tail are long. L. cumeri measures 1-|- feet in length.
Lagostomus, again, has but one species, L. trichodactylus. The
animal has a tail about half the length of the body. The digits
are reduced as compared with Chinchilla, there being but four on
the fore- and three on the hind-feet. There are only twelve dorsal
vertebrae, and seven ribs reach the sternum. In the skull a dis-
tinguishing mark from the last two genera is the separation of
the infra-orbital foramen into two by a thin lamella of bone. The
large intestine is between one-half and one-third the length
of the small intestine, and thus differs much from that of
1 AJO. account of the three genera is to 6e found in Trans, Zool. Soc. i. 1833,
p. 8&, hy Mr. E. T. Bennett.